Input/output design of the programs is carefully chosen. It facilitates running on big parallel machines, using queues etc.

The design is simplistic and seems to be used across many other computational packages, for instance SIESTA, deMon, ADF, NWChem and many others.

Programs can be started from every type of terminal applications. A terminal application should allow to change (go to) to any directory of the file system, as well as to create new directories and execute programs.

The programs use an input file (named tddft_lr.inp) to set calculation parameters.

The input file must be located in the directory where the program is started: current directory.

At the beginning of execution, the program would read (input) parameters from the input file.

Second step is typically an import of data from external program (for instance SIESTA), according to parameters from input file.

The data files from external program must be also present in the current directory.

Typically, it is most convenient to assign different directories for different physical systems/situations.

Typically, it is most convenient to start new calculation not from scratch, but modifying some working example.

In simple cases, it is most convenient to start programs in the same directory, where a DFT package was running.

Output data reside in several files and in the standard output stream stdout.

Names of generated files are typically printed to stdout.

Program can stop before calculation is complete. Examination of program output (stdout and stderr streams) gives the clue on the cause of stop.